Composition containing vinyl polymer and a bicycloheptene dicarboxylic acid-glycol polyester and process for making the polyester



Unite John R. Caldwell and John W. Tamblyn, Kingsport, Tenn., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Feb. 6, 1957, Ser. No. 638,441 9 Claims. (Cl. 26031.6)

This invention relates to plastic compositions composed of vinyl resins or of cellulose esters which are stabilized against degradation during exposure to heat. More particularly this invention concerns the use of polymeric esters of bicyclo-(2.2.1)--heptene-2,3-dicarboxylic acid with certain glycols.

Plastic materials such as the vinyl polymers and cellulose esters are subject to various types of thermal degradations caused by traces of mineral acids, present either as initial impurities or generated in the plastic during exposure to heat. In the cellulose esters, this degradation takes the form of molecular-weight breakdown with consequent loss of strength and toughness. In the polyvinyl plastics such as polyvinyl chloride, degradation takes the form of discoloration.

In the past various types of acid absorbers have been used to produce stabilization of these plastics against the damaging effects of heat. For instance, alkaline inorganic pigments like magnesium carbonate or organic acid absorbers such as the epoxy compounds have been widely used for this purpose. The organic absorbers have been considered more effective than the inorganic absorbers. However, for general use, particularly for films and fibers, a stabilizer which has less tendency to escape from the plastic by evaporation or leaching is desirable for maximum permanence of stabilizing action. We have found that certain polymeric derivatives containing the bicycleheptene structure satisfies this need. These derivatives are low-molecular-weight polyesters made by condensing bicyclo(2.2.1)-5-heptene-2,3-dicarboxylic acid with certain glycols.

One object of this invention is to provide a plastic material from cellulose esters or polyvinyl materials stabilized against degradation from exposure to heat. Another object of this invention is to provide a process for stabilizing cellulose esters and polyvinyl chloride plastic compositions against deterioration at elevated temperatures. An additional object is to provide a material which may be used for stabilizing organic plastic materials against heat degradation. A further object is to provide a low-molecular-weight polyester from bicyclo- (2.2.1 -S-heptene-2,3-dicarboxylic acid.

To prepare the polymeric composition which we have found extremely suitable for stabilizing plastic materials against heat, three molecular proportions of bicycle- (2.2.l)-S-heptene-2,3-dicarboxylic anhydride and four molecular proportions of ethylene glycol are heated at 180 C. for two hours in a nitrogen atmosphere. The temperature is then raised to 220 C. and held for three hours. The product is a viscous syrup having a molecular weight of 600-700 that was soluble in the common solvents such as acetone, alcohol, and methylene chloride. Butenediol-1,4, propylene glycol and butylene glycol may be used in place of ethylene glycol.

The low-molecular-weight polyesters used in the process of the invention may be prepared by using a ratio of 2-5 molecular proportions of bicyclo-(2.2.1)-5-l1eptone-2,3-dicarboxylic acid, or suitable derivative, with Patent 0 ice 3-6 molecular proportions of the glycol. The acid may be used in the form of its anhydride or lower alkyl ester. When the polymer is made with butenediol, it is preferred to use a lower alkyl ester of the acid, and an ester interchange catalyst such as titanium butoxide, litharge, or calcium oxide.

The reaction is preferably carried out in two stages. In the first stage the reactants are heated at 140-180 C. for 2-4 hours and in the second stage at 200-220 C. for 2-4 hours.

The polyesters have a molecular weight in the range of 500-1800.

The following examples are intended to illustrate our invention but are not intended to limit it in any way:

EXAMPLE 1 Polyvinyl chloride (Geon 101) was roll-compounded with 30% by weight of dioctyl phthalate and sheeted off the roll in the form of slabs mils thick. Similar compoundings were prepared containing, in addition, 4% by weight of the short-chain length polyester made from bicyclo-(2.2.1)-5-l1eptene-2,3-dicarboxylie acid and ethylene glycol or 4% by weight of the short-chain length polyester made from the same diacid and butenediol. Samples of these compoundings were heated between glass plates in an air oven, and observed from time to time to follow the progress of discoloration. The oven temperature was about 130 C. at the start and was set to rise at the rate of about 30 C. per hour. The results, given in Table I, show that the bicycloheptene polyesters, particularly that made with the unsaturated glycol, produced a substantial improvement in the resistance of polyvinyl chloride plastic to discoloration by heat.

Table I Color of Sample After Heating Stabilizer 30 Min. 60 Min. Min. Min.

None light brown. dark black,

brown brown. Bicycloheptenc p olye s t e r light orange red dark red.

with ethylene glycol. orange Bleycloheptene p o 1 ye st e r do. light rcddlsh reddish with butcuedlol. orange. orange. brown.

EXAMPLE 2 Cellulose acetate butyrate (13% acetyl, 38% butyryl) was roll-compounded with 12% by weight of dibutyl sebacate and sheeted oil the roll in the form of slabs 75 mils thick. Similar compoundings were prepared containing, in addition, 1% by weight of the ethylene glycol or butenediol polyester of Example 1. Samples of these compoundings were heated between glass plates in an air oven, and observed from time to time to follow the progress of discoloration. The oven temperature was about C. at the start and was set to rise at the rate of about 25 C. per hour. The results, given in Table II, show that the bicycloheptene polyesters produced a substantial improvement in the resistance of 3 Samples of these same compositions were heated for half an hour at 250 C. and the degradation of the cellulose acetate butyrate determined by measurement of the inherent viscosity, {1;} before and after heating. {1 was defined as:

where 1;, is the ratio of the viscosity of solution to that of solvent and c is the concentration of the cellulose acetate butyrate in g. per 100 cc. solvent. The solvent used was acetone, the temperature 25.0" C., and the concentration of the cellulose ester 0.23 g. per 100 cc. acetone. {17} before heating had the value of 1.40. The breakdown results, recorded in Table III, show a worthwhile improvement produced by addition of the bicycloheptene esters.

The same samples were also heated at 205 C. for one and two hours. The color developed after these heating 4 EXAMPLE 4 Sixteen g. of a copolymer of vinyl chloride and vinyl acetate (Bakelite VYNS), containing 89% vinyl chloride, was dissolved in 100 cc. of methylene chloride to make a dope which was coated and dried to give a film about 6 mils thick. Similar films were made from dopes to which had been added in one case 4 g. of diethylbicyclo-(2.2.1)-5-heptene-2,3-dicarboxylate and in the other case 4 g. of the ethylene glycol polyester of Example 1.

Samples of these films were suspended in a mechanical convection oven at 125 C. and observed every two hours for weight loss and development of color. The results, given in Table V, show that the monomeric stabilizer protects the resin well only until it is lost from the film by evaporation. Over 75% of this stabilizer escaped during six hours heating. The superiority of the polymeric stabilizer is clearly demonstrated for the longer heat treatments. Practically none of this stabilizer escaped o periods was graded by comparison with a set of color during SIX hours heating.

Table V STABILIZATION OF VYNS FILMS Weight Loss (percent) after Heating at 125 Color after Heating at 125 C. for- Stabilizer O. for- 2 H1". 4 Hr. 6 HI. 0 HI. 2 Hr. 4 Hr. 6 Hr. 8 Hr.

None 2.90 3.06 3.11 None.. Light ycllow- Yellow- YelloW- Yellowbrown. brown. brown. brown. t sl i yclo-taan-5-he tene-2,3- 13.2 15.4 16.7 do None Light Brownish- Purplislidicarboxylata. P p D Dle. brown. Bicycloheptenepolyester-with ethyl- 2.16 2.36 2.51 do Very pale straw. Very pale Pale straw. Pale straw.

ene glycol. straw.

standards. Color before heating was also determined and these color results included in Table III.

Table III Color After Heating after Original at 205 C. for Stabilizer 0.5 hr. at Color 1 hr. 2 hr. None 0.81 60 Btcycloheptcne p o l y e st e r with ethylene glycoL. 0. 91 35 65 70 Bicycloheptene polyester with butenediol 0.90 60 65 EXAMPLE 3 Table IV Color of Sample After Heating Stabilizing Plastielzer m 40 Min. 70 Min. 100 Min.

None orange dark redblack,

brown. Bicyclohcptene polyester with light yellow". orange. orange.

ethylene glycol. Bicycloheptene polyester with .do orangebrown.

butenediol. red.

Cellulose esters which may be stabilized using our new polymeric stabilizer include cellulose acetate, cellulose nitrate, and mixed esters such as cellulose acetate butyrate, cellulose acetate propionate and the like. Vinyl compounds which may be plasticized include vinyl chloride, copolymers of vinyl chloride and vinyl acetate, polystyrene, and the like.

Modifications of the invention other than as described will be apparent to those skilled in the art and the scope of the invention is limited only by the appended claims.

We claim:

1. A composition containing (1) an organic syntheticpolymer selected from the group consisting of polyvinyl chloride, copolymers of vinyl chloride and vinyl acetate and polystyrene; and (2) a polyester having a molecular weight of 5004800 obtained by condensing bicyclo- (2.2.1)-5-heptene-2,3-dicarboxylic acid with a glycol selected from the class consisting of ethylene glycol, propylene glycol, butylene glycol and butenediol.

2. A composition containing (1) an organic synthetic polymer selected from the class consisting of polyvinyl chloride, copolymers of vinyl chloride and vinyl acetate and polystyrene and; (2) a polyester having a molecular weight of 5004800 obtained by condensing bicyclo- (2.2.l)-5-heptene-2,3-dicarboxylic acid with ethylene glycol.

3. A composition containing (1) an organic synthetic polymer selected from the class consisting of polyvinyl chloride, copolymers of vinyl chloride and vinyl acetate and polystyrene and; (2) a polyester having a molecular weight of 500l800 obtained by condensing bicyclo- (2.2.1)-5-heptene-2,3-dicarboxylic acid with propylene glycol.

4. A composition containing (1) an organic synthetic polymer selected from the class consisting of polyvinyl chloride, copolymers of vinyl chloride and vinyl acetate and polystyrene and; (2) a polyester having a molecular Weight of 500-1800 obtained by condensing bicyclo- (2.2.1)-5-heptene-2,3-dicarboxylic acid with butylene glycol.

5. A composition containing (1) an organic synthetic heptene-2,3-dicarboxylic anhydride with 3-6 molecular polymer selected from the class consisting of polyvinyl proportions of a glycol selected from the class consisting chloride, copolymers of vinyl chloride and vinyl acetate of ethylene glycol, propylene glycol, butylene glycol, and and polystyrene and; (2) a polyester having a molecular hntenediol at 140-180 C. for 2-4 hours in a nitrogen weight of 500-1800 obtained by condensing bicyclo- 5 atmosphere. (2.2.1)-5-heptene-2,3-dicarboxylic acid with butenediol. 9. A process for obtaining polyesters of bicycle- 6. A composition comprising polyvinyl chloride and a (2.2.1)-5-heptene-2,3-dicarboxylic acid having a molecstabilizer, said stabilizer being a polyester having a moleca ght f 5 0- 0 c mprising ad ixing three ular weight oi 500-1800 obtain by condensing bicyclomolecular proportions of bicycle-(2.2.1)-5-heptene-2,3- (2.2.1)-5-heptene-2,3-dicarboxylic acid with ethylene dicarboxylic anhydride and fourmolecular proportions of glycol. ethylene glycol, heating for two hours at 180 C. in a 7. A process for the preparation of polyesters of nitrogen atmosphere, and then heating for a period of bicycle-(2.2.1)-5-heptene-2,3-dicarboxylic acid having a three hours at a temperature of 220 C. in a nitrogen at.- rnolecular weight of 500-1800 comprising condensing mosphere. three molecular proportions of bicycle-(2.2.1)-5-heptene- 2,3-dicarboxylic anhydride with four molecular propor- References Cited in the file of this patent tions of a glycol selected from the class consisting of ethylene glycol, propylene glycol, butylene glycol and UNITED STATES PATENTS butenediol by admixing and heating at 180 C. for two 2,311,260 Staff Feb. 16, 1943 hours in a nitrogen atmosphere, followed by heating for 2,384,855 Soday Sept. 18, 1945 three hours at a temperature of 220 C. in a nitrogen at- 2,394,815 Soday Feb. 12, 1946 mosphere. 2,766,273 Bruins et al Oct. 9, 1956 8. A process for the preparation of polyesters of bi- 2,794,812 Phillips et al June 4, 1957 cyclo-(2.2.1)-5-heptene-2,3-dicarboxylic acid having a molecular weight of 500-1800 comprising admixing and FOREIGN PATENTS heating 2-5 molecular proportions of bicyclo-(2.2.1)-5- 515,865 Canada Aug. 23, 1955 

1. A COMPOSITION CONTAINING (1) AN ORGANIC SYNTHETIC POLYMER SELECTED FROM THE GROUP CONSISTING OF POLYVINYL CHLORIDE, COPOLYMERS OF VINYL CHLORIDE AND VINYL ACETATE AND POLYSTYRENE, AND (2) A POLYESTER HAVING A MOLECULAR WEIGHT OF 500-1800 OBTAINED BY CONDENSING BICYCLO(2,2,1)-5-HEPTENE-2,3-DICARBOXYLIC ACID WITH A GLYCOL SELECTED FROM THE CLASS CONSISTING OF ETHYLENE GLYCOL, PROPYLENE GLYCOL, BUTYLENE GLYCOL AND BUTENEDIOL. 